Re: Blobs, byte[] and ByteBuffer

[Scott Gray]

On 12/09/2010, at 2:57 AM, Adrian Crum wrote:

> --- On Sat, 9/11/10, Scott Gray <scott.g...@hotwaxmedia.com> wrote:
>> Currently
>> JdbcValueHandler.BlobJdbcValueHandler will accept byte
>> arrays and Blobs (reluctantly) but not ByteBuffers. 
>> The problem is that the service engine uses ByteBuffer as
>> the attribute type for attributes created based on blob
>> entity fields and crud services fail due to this because
>> they don't attempt to convert them before using something
>> like <create-value/>.
>> 
>> So what is the correct behavior?  Should the service
>> engine be using a different type or should the
>> JdbcValueHandler be more flexible?
> 
> I'm pretty sure the current JdbcValueHandler code contains the same logic as 
> the original switch statement, but I might have missed something.

Thanks for the info, it looks like the code used to check for byte[] then 
ByteBuffer and then finally Blob, snippet below from about a year ago:

            case 12:
                if (fieldValue instanceof byte[]) {
                    sqlP.setBytes((byte[]) fieldValue);
                } else if (fieldValue instanceof ByteBuffer) {
                    sqlP.setBytes(((ByteBuffer) fieldValue).array());
                } else {
                    sqlP.setValue((java.sql.Blob) fieldValue);
                }
                break;

> That code is a bit messy because it's trying to convert multiple types to a 
> BLOB - in an effort to maintain backward compatibility. You can see remarks 
> in there about that.
> 
> I introduced new data types - Object and byte[], to help make things less 
> ambiguous and hopefully provide a path toward cleaning some of that up.
> 
> So, a discussion about which data type to use or support would be worthwhile. 
> I think the answer lies in analyzing what is being stored as a BLOB and use 
> the correct Java data type for it. If it's a serialized Object, then use an 
> Object data type. If it's a byte array that holds the contents of a file, 
> then use a byte array, etc. I imagine such an analysis would break down in 
> the Content component - where the Java data type might be unknown.
> 
> I know this doesn't answer your question, I'm just sharing things I've 
> learned and thoughts I've had on the subject.
> 
> -Adrian

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